Understanding ATC on my Refractometer

[redfishbluefish]

As the temperature drops in my unheated basement, where I make and store RO/DI water, I recently pondered the function of my refractometer. If I were to measure the salinity of the water when it was cold, I'd get a much higher number compaired to once it was heated up to temperature. I've always known this....and just thought the ATC on my refractometer was shot. But as I scratched my head, and gave this a bit of brain power, I'm now thinking the number is real, because colder water is "denser," and would therefore have a higher number. Not knowing much about the ATC, is it supposed to correct for this density change as well?

FYI, in practice I only rely on the refractometer number of heated water.

 

[Brew12]

As the temperature drops in my unheated basement, where I make and store RO/DI water, I recently pondered the function of my refractometer. If I were to measure the salinity of the water when it was cold, I'd get a much higher number compaired to once it was heated up to temperature. I've always known this....and just thought the ATC on my refractometer was shot. But as I scratched my head, and gave this a bit of brain power, I'm now thinking the number is real, because colder water is "denser," and would therefore have a higher number. Not knowing much about the ATC, is it supposed to correct for this density change as well?

FYI, in practice I only rely on the refractometer number of heated water.

It doesn't compensate for the temperature of the water at all. It compensates for the temperature of the refractometer itself. The water will match the refractometers temperature almost immediately since it is just a drop or two.